#include <stdio.h>
int main()
{
    int n, i;
    printf("please enter a integer number,n=?");
    scanf("%d", &n);
    for (i = 2; i < n; i++)
    {
        if (n % i == 0)
        break;
    }    
    if (i < n)
        printf("%d is not a prime number.\n",n);
    else
        printf("%d is a prime number.\n",n);
    return 0;
}